AEM 6.5.10 - Core Components alternate language inside the head meta not working

Currently using AEM Core components v2.18.0

I am trying to leverage the OOTB functionality for generating the Alternate Languages for page meta tags. I see the OOTB code under /apps/core/wcm/components/page/v2/page/head.links.html

Below is the piece of code which is responsible for generating it.

<link data-sly-test="${page.alternateLanguageLinks}"
data-sly-repeat="${page.alternateLanguageLinks.entrySet}"
rel="alternate" hreflang="${item.key.toLanguageTag}" href="${item.value}">

Below is my page structure

/content/<my-site>/en/<child-pages>

/content/<my-site>/ja/<child-pages>

/content/<my-site>/zh/<child-pages>

.

.

etc

But the above piece of code always generates empty.

Also i found the implementation of the code in Github

https://github.com/adobe/aem-core-wcm-components/blob/a7e377c6810dd2125a902d3ef3df5c92ec2a1719/bundles/core/src/main/java/com/adobe/cq/wcm/core/components/internal/models/v2/PageImpl.java

Can someone please explain what is com.adobe.aem.wcm.seo.SeoTags; and how to get the above code working. Am i missing some configration?